Brain activation in PTSD in response to trauma-related stimuli

Association between posttraumatic stress disorder severity and amygdala habituation to fearful stimuli

BACKGROUND

Amygdala hyperreactivity to threat has been proposed to be a causal contributor to posttraumatic stress disorder (PTSD). However, emerging literature in healthy samples shows higher test-retest reliability for amygdala habituation (the change over time in response to repeated stimuli) than for its reactivity to threat. Amygdala habituation has received relatively little attention in relationship to PTSD, despite the key role of this region in the etiology of the disorder. Thus, we investigated habituation to repeated fearful face stimuli and PTSD, in a large sample of trauma exposed African American women.

METHODS

African American women (N = 100) were recruited from a nonprofit hospital serving a largely low-income population with a high risk of trauma exposure. Participants underwent functional magnetic resonance imaging, passively viewing fearful and neutral face stimuli, and reported their history of trauma exposure and current PTSD symptoms. We examined associations between PTSD symptom severity and amygdala reactivity (fearful > neutral) and habituation (early > late) to fearful faces. Secondary analyses tested whether amygdala habituation to fearful faces mediated the association between childhood trauma and PTSD.

RESULTS

PTSD symptom severity and PTSD status (based on self-report measure) were both positively associated with amygdala habituation to repeated fearful face stimuli. Whole-brain analysis showed that this association extended to the bilateral hippocampus and left fusiform gyrus. The association held when controlling for trauma history and depressive symptoms. Amygdala habituation to fearful faces partially mediated the association between childhood trauma severity and PTSD symptom severity.

CONCLUSION

Individuals with greater PTSD symptom severity showed greater amygdala habituation to social threat cues (fearful faces), and greater habituation may partly explain the association between childhood trauma exposure and current PTSD symptoms. Further examination of the dynamics of the amygdala response to threat cues may lead to new insights in the understanding and treatment of stress-related disorders.

The effects of trauma on brain and body: A unifying role for the midbrain periaqueductal gray

Post-traumatic stress disorder (PTSD), a diagnosis that may follow the experience of trauma, has multiple symptomatic phenotypes. Generally, individuals with PTSD display symptoms of hyperarousal and of hyperemotionality in the presence of fearful stimuli. A subset of individuals with PTSD; however, elicit dissociative symptomatology (i.e., depersonalization, derealization) in the wake of a perceived threat. This pattern of response characterizes the dissociative subtype of the disorder, which is often associated with emotional numbing and hypoarousal. Both symptomatic phenotypes exhibit attentional threat biases, where threat stimuli are processed preferentially leading to a hypervigilant state that is thought to promote defensive behaviors during threat processing. Accordingly, PTSD and its dissociative subtype are thought to differ in their proclivity to elicit active (i.e., fight, flight) versus passive (i.e., tonic immobility, emotional shutdown) defensive responses, which are characterized by the increased and the decreased expression of the sympathetic nervous system, respectively. Moreover, active and passive defenses are accompanied by primarily endocannabinoid- and opioid-mediated analgesics, respectively. Through critical review of the literature, we apply the defense cascade model to better understand the pathological presentation of defensive responses in PTSD with a focus on the functioning of lower-level midbrain and extended brainstem systems.

Fear Without Context: Acute Stress Modulates the Balance of Cue-Dependent and Contextual Fear Learning

During a threatening encounter, people can learn to associate the aversive event with a discrete preceding cue or with the context in which the event took place, corresponding to cue-dependent and context-dependent fear conditioning, respectively. Which of these forms of fear learning prevails has critical implications for fear-related psychopathology. We tested here whether acute stress may modulate the balance of cue-dependent and contextual fear learning. Participants ( N = 72) underwent a stress or control manipulation 30 min before they completed a fear-learning task in a virtual environment that allowed both cued and contextual fear learning. Results showed equally strong cue- and context-dependent fear conditioning in the control group. Stress, however, abolished contextual fear learning, which was directly correlated with the activity of the stress hormone cortisol, and made cue-dependent fear more resistant to extinction. These results are the first to show that stress favors cue-dependent over contextual fear learning.

Dissociative identity as a continuum from healthy mind to psychiatric disorders: Epistemological and neurophenomenological implications approached through hypnosis

The topic of multiple personality, redefined as Dissociative Identity Disorders (DIDs) in the DSM-5, is an intriguing and still debated disorder with a long history and deep cultural and epistemological implications, extending up to the idea of possession. Hypnosis is an appealing and valuable model to manipulate subjective experience and get an insight on both the physiology and the pathophysiology of the mind-brain functioning; it and has been closely connected with DIDs and possession since its origin in 18th century and as recently proved the capacity to yield a loss of sense of agency, mimicking delusions of alien control and spirit possession. In this study we report on five very uncommon "hypnotic virtuosos" (HVs) free from any psychiatric disorder, spontaneously undergoing the emergence of multiple identities during neutral hypnosis; this allowed us to check the relationship between their experience and fMRI data. During hypnosis the subjects underwent spontaneous non-intrusive experiences of other selves which were not recalled after the end of the session, due to post-hypnotic amnesia. The fMRI showed a significant decrease of connectivity in the Default Mode Network (DMN) especially between the posterior cingulate cortex and the medial prefrontal cortex. Our results and their contrast with the available data on fMRI in DIDs allows to draw the hypothesis of a continuum between healthy mind - where multiple identities may coexist at unconscious level and may sometimes emerge to the consciousness - and DIDs, where multiple personalities emerge as dissociated, ostensibly autonomous components yielding impaired functioning, subject's loss of control and suffering. If this is the case, it seems more reasonable to refrain from seeking for a clear-cut limit between normality (anyway a conventional, statistical concept) and pathology, and accept a grey area in between, where ostensibly odd but non-pathological experiences may occur (including so-called non-ordinary mental expressions) without calling for treatment but, rather, for being properly understood.

Emerging Approaches to Neurocircuits in PTSD and TBI: Imaging the Interplay of Neural and Emotional Trauma

Posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) commonly co-occur in general and military populations and have a number of overlapping symptoms. While research suggests that TBI is risk factor for PTSD and that PTSD may mediate TBI-related outcomes, the mechanisms of these relationships are not well understood. Neuroimaging may help elucidate patterns of neurocircuitry both specific and common to PTSD and TBI and thus help define the nature of their interaction, refine diagnostic classification, and may potentially yield opportunities for targeted treatments. In this review, we provide a summary of some of the most common and the most innovative neuroimaging approaches used to characterize the neural circuits associated with PTSD, TBI, and their comorbidity. We summarize the state of the science for each disorder and describe the few studies that have explicitly attempted to characterize the neural substrates of their shared and dissociable influence. While some promising targets in the medial frontal lobes exist, there is not currently a comprehensive understanding of the neurocircuitry mediating the interaction of PTSD and TBI. Future studies should exploit innovative neuroimaging approaches and longitudinal designs to specifically target the neural mechanisms driving PTSD-TBI-related outcomes.

Current understanding of fear learning and memory in humans and animal models and the value of a linguistic approach for analyzing fear learning and memory in humans

Fear is an emotion that serves as a driving factor in how organisms move through the world. In this review, we discuss the current understandings of the subjective experience of fear and the related biological processes involved in fear learning and memory. We first provide an overview of fear learning and memory in humans and animal models, encompassing the neurocircuitry and molecular mechanisms, the influence of genetic and environmental factors, and how fear learning paradigms have contributed to treatments for fear-related disorders, such as posttraumatic stress disorder. Current treatments as well as novel strategies, such as targeting the perisynaptic environment and use of virtual reality, are addressed. We review research on the subjective experience of fear and the role of autobiographical memory in fear-related disorders. We also discuss the gaps in our understanding of fear learning and memory, and the degree of consensus in the field. Lastly, the development of linguistic tools for assessments and treatment of fear learning and memory disorders is discussed.

Inflammation and post-traumatic stress disorder

While post-traumatic stress disorder (PTSD) is currently diagnosed based solely on classic psychological and behavioral symptoms, a growing body of evidence has highlighted a link between this disorder and alterations in the immune and inflammatory systems. Epidemiological studies have demonstrated that PTSD is associated with significantly increased rates of physical comorbidities in which immune dysregulation is involved, such as metabolic syndrome, atherosclerotic cardiovascular disease, and autoimmune diseases. In line with this, a number of blood biomarker studies have reported that compared to healthy controls, individuals with PTSD exhibit significantly elevated levels of proinflammatory markers, such as interleukin-1β, interleukin-6, tumor necrosis factor-α, and C-reactive protein. Moreover, various lines of animal and human research have suggested that inflammation is not only associated with PTSD but also can play an important role in its pathogenesis and pathophysiology. In this review, we first summarize evidence suggestive of increased inflammation in PTSD. We then examine findings that suggest possible mechanisms of inflammation in this disorder in terms of two different but interrelated perspectives: putative causes of increased proinflammatory activities and potential consequences that inflammation generates. Given that there is currently a dearth of treatment options for PTSD, possibilities of new therapeutic approaches using pharmacological and non-pharmacological treatments/interventions that have anti-inflammatory effects are also discussed. Despite the increasing attention given to the inflammatory pathology of PTSD, there remains much to be elucidated, including more detailed mechanisms of inflammation, potential usefulness of inflammatory biomarkers as diagnostic and prognostic markers, and efficacy of novel treatment strategies targeting inflammation.

Systemic Cellular Activation Mapping of an Extinction-Impaired Animal Model

Fear extinction diminishes conditioned fear responses and impaired fear extinction has been reported to be related to anxiety disorders such as post-traumatic stress disorder (PTSD). We and others have reported that 129S1/SvImJ (129S1) strain of mice showed selective impairments in fear extinction following successful auditory or contextual fear conditioning. To investigate brain regions involved in the impaired fear extinction of 129S1 mice, we systemically analyzed c-Fos expression patterns before and after contextual fear conditioning and extinction. After fear conditioning, 129S1 mice showed significantly increased c-Fos expression in the medial division of the central amygdala (CEm), prelimbic (PL) cortex of the medial prefrontal cortex (mPFC), and dorsal CA3 of the hippocampus, compared to that of control C57BL/6 mice. Following fear extinction, 129S1 mice exhibited significantly more c-Fos-positive cells in the CEm, PL, and paraventricular nucleus of the thalamus (PVT) than did C57BL/6 mice. These results reveal the dynamic circuitry involved in different steps of fear memory formation and extinction, thus providing candidate brain regions to study the etiology and pathophysiology underlying impaired fear extinction.

A Rodent Model of Exposure Therapy: The Use of Fear Extinction as a Therapeutic Intervention for PTSD

The symptoms of post-traumatic stress disorder (PTSD) include cognitive impairment related to medial prefrontal cortical dysfunction. Indeed, a deficit of cognitive flexibility, i.e., an inability to modify previously learned thoughts and behaviors based on changes in the environment, may underlie many of the other symptoms of PTSD, such as changes in mood, hyper-arousal, intrusive thoughts, exaggerated and over-generalized fear, and avoidance behavior. Cognitive-behavioral therapies target the cognitive dysfunction observed in PTSD patients, training them to recalibrate stress-related perceptions, interpretations and responses. Preclinically, the extinction of conditioned fear bears resemblance to one form of cognitive therapy, exposure therapy, whereby an individual learns, through repeated exposure to a fear-provoking stimulus in a safe environment, that the stimulus no longer signals imminent threat, and their fear response is suppressed. In this review article, we highlight recent findings from our lab using fear extinction as a preclinical model of exposure therapy in rodents exposed to chronic unpredictable stress (CUS). We specifically focus on the therapeutic effects of extinction on stress-compromised set-shifting as a measure of cognitive flexibility, and active vs. passive coping behavior as a measure of avoidance. Finally, we discuss mechanisms involving activity and plasticity in the medial prefrontal cortex (mPFC) necessary for the therapeutic effects of extinction on cognitive flexibility and active coping.

Impaired inhibition as an intermediate phenotype for PTSD risk and treatment response

Inhibition of fear involves learning and then appropriately responding to safety signals, and has been shown to be impaired in PTSD patients. Response inhibition refers to cognitive control and likely uses the same prefrontal cortex circuits as fear inhibition, and has also been implicated in PTSD. Impaired inhibition can serve as an intermediate phenotype for PTSD and can be measured with neuroimaging and psychophysiological tools. We first review the neurobiological mechanisms of fear and response inhibition. Next, we summarize the functional magnetic resonance imaging (fMRI) and psychophysiological studies using fear and response inhibition paradigms in PTSD patients. Finally, we evaluate the theranostic role of impaired inhibition in PTSD risk and treatment response.

A Review of fMRI Affective Processing Paradigms Used in the Neurobiological Study of Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a chronic and debilitating psychiatric disorder with a complex clinical presentation. The last two decades have seen a proliferation of literature on the neurobiological mechanisms subserving affective processing in PTSD. The current review will summarize the neuroimaging results of the most common experimental designs used to elucidate the affective signature of PTSD. From this summary, we will provide a heuristic to organize the various paradigms discussed and report neural patterns of activations using this heuristic as a framework. Next, we will compare these results to the traditional functional neurocircuitry model of PTSD and discuss biological and analytic variables which may account for the heterogeneity within this literature. We hope that this approach may elucidate the role of experimental parameters in influencing neuroimaging findings.

Brain activation during disorder-related script-driven imagery in panic disorder: a pilot study

Despite considerable effort, the neural correlates of altered threat-related processing in panic disorder (PD) remain inconclusive. Mental imagery of disorder-specific situations proved to be a powerful tool to investigate dysfunctional threat processing in anxiety disorders. The current functional magnetic resonance imaging (fMRI) study aimed at investigating brain activation in PD patients during disorder-related script-driven imagery. Seventeen PD patients and seventeen healthy controls (HC) were exposed to newly developed disorder-related and neutral narrative scripts while brain activation was measured with fMRI. Participants were encouraged to imagine the narrative scripts as vividly as possible and they rated their script-induced emotional states after the scanning session. PD patients rated disorder-related scripts as more arousing, unpleasant and anxiety-inducing as compared to HC. Patients relative to HC showed elevated activity in the right amygdala and the brainstem as well as decreased activity in the rostral anterior cingulate cortex, and the medial and lateral prefrontal cortex to disorder-related vs. neutral scripts. The results suggest altered amygdala/ brainstem and prefrontal cortex engagement and point towards the recruitment of brain networks with opposed activation patterns in PD patients during script-driven imagery.

Memory bias and its association with memory function in women with posttraumatic stress disorder

BACKGROUND

Memory abnormalities are among a central feature of posttraumatic stress disorder (PTSD). It is suggested that individuals with PTSD exhibit memory bias; while evidence shows poor memory function in these individuals. We aimed to examine memory bias in PTSD patients relative to controls and to explore an association between memory bias and memory function.

METHODS

Forty-six women with DSM-IV PTSD, most of whom developed the disorder after interpersonal violence, and 68 non-trauma-exposed healthy control women were studied. Memory bias was assessed by a recognition memory task using negative, neutral, and positive words. Memory function was assessed by a standardized neuropsychological test battery. Depression and anxiety symptoms were assessed by self-report measures.

RESULTS

Compared to controls, patients showed significantly greater negative bias scores (i.e., correctly recognized rates for negative words minus those for neutral words) and poorer memory function. Negative bias scores were significantly correlated with worse memory function in patients. When patients were divided into those with lower vs. normal memory function, the former patients had significantly greater negative bias than the latter patients and controls. Memory bias scores in patients were not significantly correlated with depression or anxiety symptoms, nor were they significantly different between patients with comorbid major depressive disorder and those without.

LIMITATIONS

The cross-sectional design and absence of the trauma-exposed non-PTSD group limited our findings.

CONCLUSIONS

PTSD patients have greater negative memory bias, which can be associated with poorer memory function. Our findings may provide an insight into the nature of memory abnormalities in PTSD.

Tempering aversive/traumatic memories with cannabinoids: a review of evidence from animal and human studies

RATIONALE

Aversive learning and memory are essential to cope with dangerous and stressful stimuli present in an ever-changing environment. When this process is dysfunctional, however, it is associated with posttraumatic stress disorder (PTSD). The endocannabinoid (eCB) system has been implicated in synaptic plasticity associated with physiological and pathological aversive learning and memory.

OBJECTIVE AND METHODS

The objective of this study was to review and discuss evidence on how and where in the brain genetic or pharmacological interventions targeting the eCB system would attenuate aversive/traumatic memories through extinction facilitation in laboratory animals and humans. The effect size of the experimental intervention under investigation was also calculated.

RESULTS

Currently available data indicate that direct or indirect activation of cannabinoid type-1 (CB1) receptor facilitates the extinction of aversive/traumatic memories. Activating CB1 receptors around the formation of aversive/traumatic memories or their reminders can potentiate their subsequent extinction. In most cases, the effect size has been large (Cohen's d ≥ 1.0). The brain areas responsible for the abovementioned effects include the medial prefrontal cortex, amygdala, and/or hippocampus. The potential role of cannabinoid type-2 (CB2) receptors in extinction learning is now under investigation.

CONCLUSION

Drugs augmenting the brain eCB activity can temper the impact of aversive/traumatic experiences by diverse mechanisms depending on the moment of their administration. Considering the pivotal role the extinction process plays in PTSD, the therapeutic potential of these drugs is evident. The sparse number of clinical trials testing these compounds in stress-related disorders is a gap in the literature that needs to be addressed.

The Innate Alarm System and Subliminal Threat Presentation in Posttraumatic Stress Disorder: Neuroimaging of the Midbrain and Cerebellum

BACKGROUND

The innate alarm system, a network of interconnected midbrain, other brainstem, and thalamic structures, serves to rapidly detect stimuli in the environment prior to the onset of conscious awareness. This system is sensitive to threatening stimuli and has evolved to process these stimuli subliminally for hastened responding. Despite the conscious unawareness, the presentation of subliminal threat stimuli generates increased activation of limbic structures, including the amygdala and insula, as well as emotionally evaluative structures, including the cerebellum and orbitofrontal cortex. Posttraumatic stress disorder (PTSD) is associated with an increased startle response and decreased extinction learning to conditioned threat. The role of the innate alarm system in the clinical presentation of PTSD, however, remains poorly understood.

METHODS

Here, we compare midbrain, brainstem, and cerebellar activation in persons with PTSD (n = 26) and matched controls (n = 20) during subliminal threat presentation. Subjects were presented with masked trauma-related and neutral stimuli below conscious threshold. Contrasts of subliminal brain activation for the presentation of neutral stimuli were subtracted from trauma-related brain activation. Group differences in activation, as well as correlations between clinical scores and PTSD activation, were examined. Imaging data were preprocessed utilizing the spatially unbiased infratentorial template toolbox within SPM12.

RESULTS

Analyses revealed increased midbrain activation in PTSD as compared to controls in the superior colliculus, periaqueductal gray, and midbrain reticular formation during subliminal threat as compared to neutral stimulus presentation. Controls showed increased activation in the right cerebellar lobule V during subliminal threat presentation as compared to PTSD. Finally, a negative correlation emerged between PTSD patient scores on the Multiscale Dissociation Inventory for the Depersonalization/Derealization subscale and activation in the right lobule V of the cerebellum during the presentation of subliminal threat as compared to neutral stimuli.

CONCLUSION

We interpret these findings as evidence of innate alarm system overactivation in PTSD and of the prominent role of the cerebellum in the undermodulation of emotion observed in PTSD.

Current and future functional imaging techniques for post-traumatic stress disorder

Posttraumatic stress disorder (PTSD) is a trauma and stressor related psychiatric disorder associated with structural, metabolic, and molecular alternations in several brain regions including diverse cortical areas, neuroendocrine regions, the striatum, dopaminergic, adrenergic and serotonergic pathways, and the limbic system. We are in critical need of novel therapeutics and biomarkers for PTSD and a deep understanding of cutting edge imaging and spectroscopy methods is necessary for the development of promising new approaches to better diagnose and treat the disorder. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criterion, all forms of traumatic stress-induced disorder are considered acute stress disorder for the first month following the stressor. Only after symptoms do not remit for one month can the disorder be deemed PTSD. It would be particularly useful to differentiate between acute stress disorder and PTSD during the one month waiting period so that more intensive treatments can be applied early on to patients with a high likelihood of developing PTSD. This would potentially enhance treatment outcomes and/or prevent the development of PTSD. Comprehension of the qualities and limitations of currently applied methods as well as the novel emerging techniques provide invaluable knowledge for fast paced development. Conventional methods of studying PTSD have proven to be insufficient for diagnosis, measurement of treatment efficacy, and monitoring disease progression. As the field currently stands, there is no diagnostic biomarker available for any psychiatric disease, PTSD included. Currently, emerging and available technologies are not utilized to their full capacity and in appropriate experimental designs for the most fruitful possible studies in this area. Therefore, there is an apparent need for improved methods in PTSD research. This review demonstrates the current state of the literature in PTSD, including molecular, cellular, and behavioral indicators, possible biomarkers and clinical and pre-clinical imaging techniques relevant to PTSD, and through this, elucidate the void of current practical imaging and spectroscopy methods that provide true biomarkers for the disorder and the significance of devising new techniques for future investigations. We are unlikely to develop a single biomarker for any psychiatric disorder however. As psychiatric disorders are incomparably complex compared to other medical diagnoses, its most likely that transcriptomic, metabolomic and structural and connectomic imaging data will have to be analyzed in concert in order to produce a dependable non-behavioral marker of PTSD. This can explain the necessity of bridging conventional approaches to novel technologies in order to create a framework for further discoveries in the treatment of PTSD.

Conventional methods of studying posttraumatic stress disorder (PTSD) have proven to be insufficient for diagnosis. We have reviewed clinical and preclinical imaging techniques as well as molecular, cellular, and behavioral indicators for PTSD.

Reward and aversion processing in patients with post-traumatic stress disorder: functional neuroimaging with visual and thermal stimuli

In patients with post-traumatic stress disorder (PTSD), a decrease in the brain reward function was reported in behavioral- and in neuroimaging studies. While pathophysiological mechanisms underlying this response are unclear, there are several lines of evidence suggesting over-recruitment of the brain reward regions by aversive stimuli rendering them unavailable to respond to reward-related content. The purpose of this study was to juxtapose brain responses to functional neuroimaging probes that reliably produce rewarding and aversive experiences in PTSD subjects and in healthy controls. The stimuli used were pleasant, aversive and neutral images selected from the International Affective Picture System (IAPS) along with pain-inducing heat applied to the dorsum of the left hand; all were administered during 3 T functional magnetic resonance imaging. Analyses of IAPS responses for the pleasant images revealed significantly decreased subjective ratings and brain activations in PTSD subjects that included striatum and medial prefrontal-, parietal- and temporal cortices. For the aversive images, decreased activations were observed in the amygdala and in the thalamus. PTSD and healthy subjects provided similar subjective ratings of thermal sensory thresholds and each of the temperatures. When 46 °C (hot) and 42 °C (neutral) temperatures were contrasted, voxelwise between-group comparison revealed greater activations in the striatum, amygdala, hippocampus and medial prefrontal cortex in the PTSD subjects. These latter findings were for the most part mirrored by the 44 vs. 42 °C contrast. Our data suggest different brain alterations patterns in PTSD, namely relatively diminished corticolimbic response to pleasant and aversive psychosocial stimuli in the face of exaggerated response to heat-related pain. The present findings support the hypothesis that brain sensitization to pain in PTSD may interfere with the processing of psychosocial stimuli whether they are of rewarding or aversive valence.

Within- and Between-Session Prefrontal Cortex Response to Virtual Reality Exposure Therapy for Acrophobia

Exposure Therapy (ET) has demonstrated its efficacy in the treatment of phobias, anxiety and Post-traumatic Stress Disorder (PTSD), however, it suffers a high drop-out rate because of too low or too high patient engagement in treatment. Virtual Reality Exposure Therapy (VRET) is comparably effective regarding symptom reduction and offers an alternative tool to facilitate engagement for avoidant participants. Neuroimaging studies have demonstrated that both ET and VRET normalize brain activity within a fear circuit. However, previous studies have employed brain imaging technology which restricts people's movement and hides their body, surroundings and therapist from view. This is at odds with the way engagement is typically controlled. We used a novel combination of neural imaging and VR technology-Functional Near-Infrared Spectroscopy (fNIRS) and Immersive Projection Technology (IPT), to avoid these limitations. Although there are a few studies that have investigated the effect of VRET on a brain function after the treatment, the present study utilized technologies which promote ecological validity to measure brain changes after VRET treatment. Furthermore, there are no studies that have measured brain activity within VRET session. In this study brain activity within the prefrontal cortex (PFC) was measured during three consecutive exposure sessions. N = 13 acrophobic volunteers were asked to walk on a virtual plank with a 6 m drop below. Changes in oxygenated (HbO) hemoglobin concentrations in the PFC were measured in three blocks using fNIRS. Consistent with previous functional magnetic resonance imaging (fMRI) studies, the analysis showed decreased activity in the DLPFC and MPFC during first exposure. The activity increased toward normal across three sessions. The study demonstrates potential efficacy of a method for measuring within-session neural response to virtual stimuli that could be replicated within clinics and research institutes, with equipment better suited to an ET session and at fraction of the cost, when compared to fMRI. This has application in widening access to, and increasing ecological validity of, immersive neuroimaging across understanding, diagnosis, assessment and treatment of, a range of mental disorders such as phobia, anxiety and PTSD or addictions.

Brain circuit dysfunction in post-traumatic stress disorder: from mouse to man

Post-traumatic stress disorder (PTSD) is a prevalent, debilitating and sometimes deadly consequence of exposure to severe psychological trauma. Although effective treatments exist for some individuals, they are limited. New approaches to intervention, treatment and prevention are therefore much needed. In the past few years, the field has rapidly developed a greater understanding of the dysfunctional brain circuits underlying PTSD, a shift in understanding that has been made possible by technological revolutions that have allowed the observation and perturbation of the macrocircuits and microcircuits thought to underlie PTSD-related symptoms. These advances have allowed us to gain a more translational knowledge of PTSD, have provided further insights into the mechanisms of risk and resilience and offer promising avenues for therapeutic discovery.

The role of suboptimal mitochondrial function in vulnerability to post-traumatic stress disorder

Post-traumatic stress disorder remains the most significant psychiatric condition associated with exposure to a traumatic event, though rates of traumatic event exposure far outstrip incidence of PTSD. Mitochondrial dysfunction and suboptimal mitochondrial function have been increasingly implicated in several psychopathologies, and recent genetic studies have similarly suggested a pathogenic role of mitochondria in PTSD. Mitochondria play a central role in several physiologic processes underlying PTSD symptomatology, including abnormal fear learning, brain network activation, synaptic plasticity, steroidogenesis, and inflammation. Here we outline several potential mechanisms by which inherited (genetic) or acquired (environmental) mitochondrial dysfunction or suboptimal mitochondrial function, may contribute to PTSD symptomatology and increase susceptibility to PTSD. The proposed pathogenic role of mitochondria in the pathophysiology of PTSD has important implications for prevention and therapy, as antidepressants commonly prescribed for patients with PTSD have been shown to inhibit mitochondrial function, while alternative therapies shown to improve mitochondrial function may prove more efficacious.

Eye movement desensitization and reprocessing as a treatment for PTSD: current neurobiological theories and a new hypothesis

Eye movement desensitization and reprocessing (EMDR), a form of psychotherapy for individuals with post-traumatic stress disorder (PTSD), has long been a controversial topic, hampered in part by a lack of understanding of the neural mechanisms that contribute to its remedial effect. Here, we review current theories describing EMDR's potential neurobiological mechanisms of action involving working memory, interhemispheric communication, de-arousal, and memory reconsolidation. We then discuss recent studies describing the temporal and spatial aspects of smooth pursuit and predictive saccades, which resemble those made during EMDR, and their neural correlates within the default mode network (DMN) and cerebellum. We hypothesize that if the production of bilateral predictive eye movements is supportive of DMN and cerebellum activation, then therapies that shift the brain towards this state correspondingly would benefit the processes regulated by these structures (i.e., memory retrieval, relaxation, and associative learning), all of which are essential components for PTSD recovery. We propose that the timing of sensory stimulation may be relevant to treatment effect and could be adapted across different patients depending on their baseline saccade metrics. Empirical data in support of this model are reviewed and experimental predictions are discussed.

The BDNF Val66Met Prodomain Disassembles Dendritic Spines Altering Fear Extinction Circuitry and Behavior

A human variant in the BDNF gene (Val66Met; rs6265) is associated with impaired fear extinction. Using super-resolution imaging, we demonstrate that the BDNF Met prodomain disassembles dendritic spines and eliminates synapses in hippocampal neurons. In vivo, ventral CA1 (vCA1) hippocampal neurons undergo similar morphological changes dependent on their transient co-expression of a SorCS2/p75^NTR receptor complex during peri-adolescence. BDNF Met prodomain infusion into the vCA1 during this developmental time frame reduces dendritic spine density and prelimbic (PL) projections, impairing cued fear extinction. Adolescent Bdnf^Met/Met mice display similar spine and PL innervation deficits. Using fiber photometry, we found that, in wild-type mice, vCA1 neurons projecting to the PL encode extinction by enhancing neural activity in threat anticipation and rapidly subsiding their response. This adaptation is absent in BDNF^Met/Met mice. We conclude that the BDNF Met prodomain renders vCA1-PL projection neurons underdeveloped, preventing their capacity for subsequent circuit modulation necessary for fear extinction. VIDEO ABSTRACT.

Role of retrosplenial cortex in processing stress-related context memories

This work summarizes evidence for the role of RSC in processing fear-inducing context memories. Specifically, we discuss molecular, cellular, and network mechanisms by which RSC might contribute the processing of contextual fear memories. We focus on glutamatergic and cholinergic mechanisms underlying encoding, retrieval, and extinction of context-dependent fear. RSC mechanisms underlying retrieval of recently and remotely acquired memories are compared to memory mechanisms of anterior cortices. Due to the strong connectivity between hippocampus and RSC, we also compare the extent to which their mechanisms of encoding, retrieval, and extinction show overlap. At a theoretical level, we discuss the role of RSC in the framework of systems consolidation as well as retrieval-induced memory modulation. Lastly, we emphasize the implication of these findings for psychopathologies associated with neurological and psychiatric disorders. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Neurotrophic factors and hippocampal activity in PTSD

Although numerous studies have investigated the neurotrophic factors and hippocampal activity in posttraumatic stress disorder (PTSD) separately each other, it is unclear whether an association between neurotrophic factors and hippocampal activity is present. The aim of this study was to evaluate the functional changes in hippocampus before and after treatment with escitalopram and to associate these changes with peptides related to neuronal growth in patients with chronic PTSD and trauma survivors without PTSD. Fifteen earthquake survivors with chronic PTSD and thirteen drug naïve trauma exposed individuals without PTSD underwent fMRI scans in a block design. Serum levels of Nerve Growth Factor (NGF) and Brain Derived Neurotrophic Factor (BDNF) were measured before and after 12 weeks treatment with escitalopram. Baseline median serum level of NGF was significantly lower in patients with chronic PTSD than trauma survivors; however, 12 weeks of treatment with escitalopram significantly increased it. Higher activation was found both in left and right hippocampus for chronic PTSD group than trauma survivors. Treatment with escitalopram was significantly associated with suppression of the hyperactivation in left hippocampus in patients with chronic PTSD. Bilateral hyperactivation in hippocampus and lowered NGF may associate with neurobiological disarrangements in chronic PTSD. Treatment with escitalopram was significantly associated with both improvement in the severity of PTSD symptoms and biological alterations. Patients diagnosed with PTSD may have further and complicated deteriorations in hippocampal networks and neurotransmitter systems than individuals who had not been diagnosed with PTSD following the same traumatic experience.

A Critical Review of Negative Affect and the Application of CBT for PTSD

Forms of cognitive and behavioral therapies (CBTs), including prolonged exposure and cognitive processing therapy, have been empirically validated as efficacious treatments for posttraumatic stress disorder (PTSD). However, the assumption that PTSD develops from dysregulated fear circuitry possesses limitations that detract from the potential efficacy of CBT approaches. An analysis of these limitations may provide insight into improvements to the CBT approach to PTSD, beginning with an examination of negative affect as an essential component to the conceptualization of PTSD and a barrier to the implementation of CBT for PTSD. As such, the literature regarding the impact of negative affect on aspects of cognition (i.e., attention, processing, memory, and emotion regulation) necessary for the successful application of CBT was systematically reviewed. Several literature databases were explored (e.g., PsychINFO and PubMed), resulting in 25 articles that met criteria for inclusion. Results of the review indicated that high negative affect generally disrupts cognitive processes, resulting in a narrowed focus on stimuli of a negative valence, increased rumination of negative autobiographical memories, inflexible preservation of initial information, difficulty considering counterfactuals, reliance on emotional reasoning, and misinterpretation of neutral or ambiguous events as negative, among others. With the aim to improve treatment efficacy of CBT for PTSD, suggestions to incorporate negative affect into research and clinical contexts are discussed.

Consolidative mechanisms of emotional processing in REM sleep and PTSD

Research suggests sleep plays a role in the consolidation of recently acquired memories for long-term storage. rapid eye movement (REM) sleep has been shown to play a complex role in emotional-memory processing, and may be involved in subsequent waking-day emotional reactivity and amygdala responsivity. Interaction of the hippocampus and basolateral amygdala with the medial-prefrontal cortex is associated with sleep-dependent learning and emotional memory processing. REM is also implicated in post-traumatic stress disorder (PTSD), which is characterized by sleep disturbance, heightened reactivity to fearful stimuli, and nightmares. Many suffers of PTSD also exhibit dampened medial-prefrontal cortex activity. However, the effects of PTSD-related brain changes on REM-dependent consolidation or the notion of 'over-consolidation' (strengthening of memory traces to such a degree that they become resistant to extinction) have been minimally explored. Here, we posit that (in addition to sleep architecture changes) the memory functions of REM must also be altered in PTSD. We propose a model of REM-dependent consolidation of learned fear in PTSD and examine how PTSD-related brain changes might interact with fear learning. We argue that reduced efficacy of inhibitory medial-prefrontal pathways may lead to maladaptive processing of traumatic memories in the early stages of consolidation after trauma.

Directed threat imagery in generalized anxiety disorder

BACKGROUND

Worrying has been suggested to prevent emotional and elaborative processing of fears. In cognitive-behavioral therapy (CBT), generalized anxiety disorder (GAD) patients are exposed to their fears during the method of directed threat imagery by inducing emotional reactivity. However, studies investigating neural correlates of directed threat imagery and emotional reactivity in GAD patients are lacking. The present functional magnetic resonance imaging (fMRI) study aimed at delineating neural correlates of directed threat imagery in GAD patients.

METHOD

Nineteen GAD patients and 19 healthy controls (HC) were exposed to narrative scripts of either disorder-related or neutral content and were encouraged to imagine it as vividly as possible.

RESULTS

Rating results showed that GAD patients experienced disorder-related scripts as more anxiety inducing and arousing than HC. These results were also reflected in fMRI data: Disorder-related v. neutral scripts elicited elevated activity in the amygdala, dorsomedial prefrontal cortex, ventrolateral prefrontal cortex and the thalamus as well as reduced activity in the ventromedial prefrontal cortex/subgenual anterior cingulate cortex in GAD patients relative to HC.

CONCLUSION

The present study presents the first behavioral and neural evidence for emotional reactivity during directed threat imagery in GAD. The brain activity pattern suggests an involvement of a fear processing network as a neural correlate of initial exposure during directed imagery in CBT in GAD.

Presynaptic α2-adrenoceptor modulates glutamatergic synaptic transmission in rat nucleus accumbens in vitro

The nucleus accumbens (NAc), integrating information from the prefrontal cortex and limbic structures, plays a critical role in reward and emotion regulation. Previous studies have reported that the NAc shell receives direct noradrenergic projections, and activation of α₂-adrenoceptor (α₂-AR) in the NAc shell decreases the fear or anxiety level of rats. However, the underlying mechanism is still little known. Intriguingly, glutamatergic neurotransmission in the NAc shell is closely related to reward and emotion. Here, using brain slice preparations and whole-cell patch clamp recordings, we examined the effect of activation of α₂-AR on glutamatergic neurotransmission in the NAc shell. Perfusing slice with α₂-AR selective agonist clonidine (CLON) reduced the evoked excitatory postsynaptic currents (EPSCs) on the NAc shell neurons. This inhibitory effect on AMPA-mediated glutamatergic EPSCs was blocked by the α₂-AR selective antagonist yohimbine (YOH). Notably, CLON reduced the frequency but not the amplitude of miniature EPSCs. Furthermore, CLON decreased the first EPSC amplitude but increased the paired-pulse facilitation on the NAc shell neurons, and it did not affect postsynaptic AMPA/NMDA ratio, revealing a presynaptic mechanism of α₂-AR-mediated inhibition on glutamatergic transmission. In addition, the modulation on glutamatergic transmission by α₂-AR was independent of presynaptic NMDA receptor. These results suggest that noradrenergic afferent inputs may suppress glutamatergic synaptic transmission via presynaptic α₂-AR in the NAc shell, and actively participate in rewarding and emotional processes via the NAc.

Persistent, generalized hypersensitivity of olfactory bulb interneurons after olfactory fear generalization

Generalization of fear from previously threatening stimuli to novel but related stimuli can be beneficial, but if fear overgeneralizes to inappropriate situations it can produce maladaptive behaviors and contribute to pathological anxiety. Appropriate fear learning can selectively facilitate early sensory processing of threat-predictive stimuli, but it is unknown if fear generalization has similarly generalized neurosensory consequences. We performed in vivo optical neurophysiology to visualize odor-evoked neural activity in populations of periglomerular interneurons in the olfactory bulb 1 day before, 1 day after, and 1 month after each mouse underwent an olfactory fear conditioning paradigm designed to promote generalized fear of odors. Behavioral and neurophysiological changes were assessed in response to a panel of odors that varied in similarity to the threat-predictive odor at each time point. After conditioning, all odors evoked similar levels of freezing behavior, regardless of similarity to the threat-predictive odor. Freezing significantly correlated with large changes in odor-evoked periglomerular cell activity, including a robust, generalized facilitation of the response to all odors, broadened odor tuning, and increased neural responses to lower odor concentrations. These generalized effects occurred within 24 h of a single conditioning session, persisted for at least 1 month, and were detectable even in the first moments of the brain's response to odors. The finding that generalized fear includes altered early sensory processing of not only the threat-predictive stimulus but also novel though categorically-similar stimuli may have important implications for the etiology and treatment of anxiety disorders with sensory sequelae.

A Functional Near-Infrared Spectroscopy Study of Trauma-Related Auditory and Olfactory Cues: Posttraumatic Stress Disorder or Combat Experience?

The prevalence of posttraumatic stress disorder (PTSD) among U.S. veterans deployed to Iraq or Afghanistan necessitates the need for comprehensive assessment and treatment strategies. This study investigated the utility of a combat-related PTSD symptom provocation paradigm to elicit unique neurological responses across three groups: combat veterans with PTSD, combat veterans without PTSD, and nonmilitary participants without PTSD. Using functional near-infrared spectroscopy (fNIRS) the results indicated that combat veterans with PTSD demonstrated significant activation to a trauma-related sound compared with nonmilitary personnel, channel 14: d = 1.03, 95% confidence interval (CI) [0.28, 1.76]; channel 15: d = 1.30, 95% CI [0.53, 2.06]; and combat veterans without PTSD, channel 14: d = 0.87, 95% CI [0.14, 1.59]. Specifically, this increased neural activation was approximately located in the right medial superior prefrontal cortex (Brodmann areas 9/10), an area associated with experiencing negative or threatening stimuli and emotional detachment. There were no differences across the groups for nontrauma-related sounds. Results were less clear with respect to a combat-related odor. These results suggest a specific neurophysiological response to trauma-related cues and, if replicated, may offer a biomarker for combat-related PTSD. Such a response could provide incremental validity over diagnostic assessments alone and assist in planning and monitoring of treatment outcome.

Impact of posttraumatic stress symptom dimensions on amygdala reactivity to emotional faces

Posttraumatic stress disorder (PTSD) is highly prevalent and associated with impairment, even at the subthreshold level. It is therefore important to identify biological processes that contribute to the pathophysiology of posttraumatic stress symptoms (PTSS). Although neuroimaging research has highlighted the importance of heightened amygdala reactivity to aversive stimuli in PTSS, not all studies have yielded evidence of this relationship. Given that PTSS is comprised of four, factor analytically distinct dimensions of symptoms - re-experiencing, avoidance, hyperarousal, and negative cognitions and mood - it is possible that heightened amygdala reactivity to aversive stimuli is specific to certain PTSS clusters. In a sample of 45 trauma-exposed individuals, the present study therefore examined how specific PTSS clusters relate to amygdala responding during functional magnetic resonance imaging (fMRI) to both negative and positive emotional faces during a well-validated social-emotional task, the Emotional Face Assessment Task (EFAT). Results indicated that hyperarousal symptoms were positively associated with left amygdala reactivity across all emotional face conditions. There was no interaction of hyperarousal by condition (i.e., fearful, sad, angry, or happy faces), and other PTSS clusters were not associated with amygdala reactivity. These results indicate that the hyperarousal cluster of PTSS may have a unique relationship with amygdala reactivity to socioemotional information. The results also corroborate a growing literature suggesting that trauma-exposed individuals characterized by high PTSS hyperarousal symptoms may display exaggerated psychophysiological reactivity to appetitive and aversive stimuli.

Context Processing and the Neurobiology of Post-Traumatic Stress Disorder

Progress in clinical and affective neuroscience is redefining psychiatric illness as symptomatic expression of cellular/molecular dysfunctions in specific brain circuits. Post-traumatic stress disorder (PTSD) has been an exemplar of this progress, with improved understanding of neurobiological systems subserving fear learning, salience detection, and emotion regulation explaining much of its phenomenology and neurobiology. However, many features remain unexplained and a parsimonious model that more fully accounts for symptoms and the core neurobiology remains elusive. Contextual processing is a key modulatory function of hippocampal-prefrontal-thalamic circuitry, allowing organisms to disambiguate cues and derive situation-specific meaning from the world. We propose that dysregulation within this context-processing circuit is at the core of PTSD pathophysiology, accounting for much of its phenomenology and most of its biological findings. Understanding core mechanisms like this, and their underlying neural circuits, will sharpen diagnostic precision and understanding of risk factors, enhancing our ability to develop preventive and "personalized" interventions.

Using the Single Prolonged Stress Model to Examine the Pathophysiology of PTSD

The endurance of memories of emotionally arousing events serves the adaptive role of minimizing future exposure to danger and reinforcing rewarding behaviors. However, following a traumatic event, a subset of individuals suffers from persistent pathological symptoms such as those seen in posttraumatic stress disorder (PTSD). Despite the availability of pharmacological treatments and evidence-based cognitive behavioral therapy, a considerable number of PTSD patients do not respond to the treatment, or show partial remission and relapse of the symptoms. In controlled laboratory studies, PTSD patients show deficient ability to extinguish conditioned fear. Failure to extinguish learned fear could be responsible for the persistence of PTSD symptoms such as elevated anxiety, arousal, and avoidance. It may also explain the high non-response and dropout rates seen during treatment. Animal models are useful for understanding the pathophysiology of the disorder and the development of new treatments. This review examines studies in a rodent model of PTSD with the goal of identifying behavioral and physiological factors that predispose individuals to PTSD symptoms. Single prolonged stress (SPS) is a frequently used rat model of PTSD that involves exposure to several successive stressors. SPS rats show PTSD-like symptoms, including impaired extinction of conditioned fear. Since its development by the Liberzon lab in 1997, the SPS model has been referred to by more than 200 published papers. Here we consider the findings of these studies and unresolved questions that may be investigated using the model.

Reduced Cortical Thickness in the Temporal Pole, Insula, and Pars Triangularis in Patients with Panic Disorder

PURPOSE

Recent neuroimaging findings have revealed that paralimbic and prefrontal regions are involved in panic disorder (PD). However, no imaging studies have compared differences in cortical thickness between patients with PD and healthy control (HC) subjects.

MATERIALS AND METHODS

Forty-seven right-handed patients with PD who met the diagnostic criteria in the Diagnostic and Statistical Manual of Mental Disorders-4th edition-text revision, and 30 HC subjects were enrolled. We used the FreeSurfer software package for estimating the cortical thickness of regions of interest, including the temporal pole, insula, and pars triangularis (mid-ventrolateral prefrontal cortex).

RESULTS

Cortical thickness of the temporal pole (p=0.033, right), insula (p=0.017, left), and pars triangularis (p=0.008, left; p=0.025, right) in patients with PD was significantly lower, compared with HC subjects (Benjamini-Hochberg false discovery rate correction). Exploratory analysis revealed a significant negative correlation between the cortical thickness of the right temporal pole and Beck Depression Inventory scores (r=-0.333, p=0.027) in patients with PD and positive correlations between the cortical thickness of the left pars triangularis and Panic Disorder Severity Scale (r=0.429, p=0.004), Anxiety Sensitivity Index-Revised (r=0.380, p=0.011), and Beck Anxiety Inventory (r=0.421, p=0.004) scores using Pearson's correlation.

CONCLUSION

Ours study is the first to demonstrate cortical thickness reduction in the temporal pole, insula, and pars triangularis in patients with PD, compared with the HC subjects. These findings suggest that reduced cortical thickness could play an important role in the pathophysiology of PD.

Ketamine promotes increased freezing behavior in rats with experimental PTSD without changing brain glucose metabolism or BDNF

Acute treatment with ketamine, an NMDA receptor antagonist, has been reported to be efficacious in treating depression. The goal of our study was to evaluate ketamine treatment in an animal model of another important psychiatric disease, post-traumatic stress disorder (PTSD). Fifty-eight male rats were initially divided into four groups: Control+Saline (CTRL+SAL), Control+Ketamine (CTRL+KET), PTSD+Saline (PTSD+SAL) and PTSD+Ketamine (PTSD+KET). To mimic PTSD we employed the inescapable footshock protocol. The PTSD animals were classified according to freezing behavior duration into "extreme behavioral response" (EBR) or "minimal behavioral response" (MBR). Afterwards, the glucose metabolism and BDNF were evaluated in the hippocampus, frontal cortex, and amygdala. Our results show that animals classified as EBR exhibited increased freezing behavior and that ketamine treatment further increased freezing duration. Glucose metabolism and BDNF levels showed no significant differences. These results suggest ketamine might aggravate PTSD symptoms and that this effect is unrelated to alterations in glucose metabolism or BDNF protein levels.

Influence of early trauma on features of schizophrenia

AIM

This proof-of-concept study examined if early trauma influences features of schizophrenia, consistent with hypothalamic-pituitary-adrenal (HPA) axis activation.

METHODS

Early trauma and current perceived stress were assessed in 28 treated schizophrenia cases, along with salivary cortisol, brain volumes, cognition and symptoms.

RESULTS

Early trauma predicted more positive (r = .66, P = .005) and dysthymia symptoms (r -.65, P = .007), but less negative symptoms (r = -.56, P = .023), as well as reduced whole brain volumes (r = .50, P = .040) and increased amygdala to whole brain volume ratios (r = .56, P = .018). Larger volume reductions accompanied cortisol levels: evening values predicted smaller whole brain and hippocampal volumes whereas afternoon levels only significantly predicted smaller brain volumes in women. Sex differences were demonstrated between early trauma and cognition, with better cognition in traumatized women than other women and no male effects. Current perceived stress was related to dysthymia (especially in women) and diminished sense of purpose and social drive (especially in men).

CONCLUSIONS

These results suggest that early trauma and current stress impact features of schizophrenia, consistent with stress sensitization and increased dopamine activity for treatment refractory positive symptoms, as well as the cascade of increased morning cortisol, reduced brain volumes, and depressive and deficit symptoms. Conversely, cognitive deficits and negative symptoms may arise from a distinct diathesis. The sex differences accord with the literature on human HPA function and stress responses. Early trauma may be a stressor in the aetiopathophysiology of schizophrenia, particularly for cases with treatment refractory positive symptoms, and may guide future treatment development.

Genesis and Maintenance of Attentional Biases: The Role of the Locus Coeruleus-Noradrenaline System

Emotionally arousing events are typically better remembered than mundane ones, in part because emotionally relevant aspects of our environment are prioritized in attention. Such biased attentional tuning is itself the result of associative processes through which we learn affective and motivational relevance of cues. We propose that the locus coeruleus-noradrenaline (LC-NA) system plays an important role in the genesis of attentional biases through associative learning processes as well as their maintenance. We further propose that individual differences in and disruptions of the LC-NA system underlie the development of maladaptive biases linked to psychopathology. We provide support for the proposed role of the LC-NA system by first reviewing work on attentional biases in development and its link to psychopathology in relation to alterations and individual differences in NA availability. We focus on pharmacological manipulations to demonstrate the effect of a disrupted system as well as the ADRA2b polymorphism as a tool to investigate naturally occurring differences in NA availability. We next review associative learning processes that-modulated by the LC-NA system-result in such implicit attentional biases. Further, we demonstrate how NA may influence aversive and appetitive conditioning linked to anxiety disorders as well as addiction and depression.

Interpersonal violence in posttraumatic women: brain networks triggered by trauma-related pictures

Interpersonal violence (IPV) is one of the most frequent causes for the development of posttraumatic stress disorder (PTSD) in women. Trauma-related triggers have been proposed to evoke automatic emotional responses in PTSD. The present functional magnetic resonance study investigated the neural basis of trauma-related picture processing in women with IPV-PTSD (n = 18) relative to healthy controls (n = 18) using a newly standardized trauma-related picture set and a non-emotional vigilance task. We aimed to identify brain activation and connectivity evoked by trauma-related pictures, and associations with PTSD symptom severity. We found hyperactivation during trauma-related vs neutral picture processing in both subcortical [basolateral amygdala (BLA), thalamus, brainstem] and cortical [anterior cingulate cortex (ACC), medial prefrontal cortex (mPFC), insula, occipital cortex] regions in IPV-PTSD. In patients, brain activation in amygdala, ACC, insula, occipital cortex and brainstem correlated positively with symptom severity. Furthermore, connectivity analyses revealed hyperconnectivity between BLA and dorsal ACC/mPFC. Results show symptom severity-dependent brain activation and hyperconnectivity in response to trauma-related pictures in brain regions related to fear and visual processing in women suffering from IPV-PTSD. These brain mechanisms appear to be associated with immediate responses to trauma-related triggers presented in a non-emotional context in this PTSD subgroup.

The Characteristics of Emotional Response of Post-traumatic Stress Disorder and Post-traumatic Growth among Chinese Adults Exposed to an Explosion Incident

Purpose

Post-traumatic stress disorder (PTSD) and post-traumatic growth (PTG) are two different outcomes that may occur after experiencing traumatic events. Meanwhile, the traumatic exposure level and emotion response played an important role in the process. The present study first evaluated the relationship between PTSD, PTG, and traumatic exposure level and then compared the characteristics of emotional response through response time of the affective priming paradigm.

Methods

For the purpose of evaluating the relationship between PTSD, PTG, and trauma exposure level, a sample of 2,395 participants completed measures of posttraumatic stress disorder Checklist-Civilian Version (PCL-C), Post-traumatic Growth Inventory (PTGI) and a trauma exposure-related survey, and Pearson’s correlation analysis for the scales were conducted. In order to compare the characteristics of emotional response between PTSD and PTG, we randomly selected 90 participants and divided them into groups of PTSD, PTG, and control according the scores of PCL-C and PTGI, then the 90 participants were asked to do the affective priming task and the response time was recorded, at last analysis of variance was employed to analyze the data.

Results

The results indicated that PTSD was not correlated with PTG. It was positively correlated with the traumatic exposure level, but PTG was not observed in this phenomenon. Finally, the data of response time showed that PTSD required more time to do the priming task and PTG demonstrated no difference compared to the control group.

Conclusion

Combined with previous research findings, the relationship between PTSD and PTG may depend on the type and severity of the trauma, the exposure level, and other such parameters. In terms of positive outcome of trauma PTG displayed no changes of emotional performance from the perspective of behavior. The preliminary results suggested that PTG was more related to a self-reported or self-experienced state.

Persistent amygdala novelty response is associated with less anterior cingulum integrity in trauma-exposed women

Objectives

We investigated the potential role of cingulum and uncinate fasciculus integrity in trauma-related neural hypervigilance, indexed by less discrimination between amygdala activation to novel and familiar affective images.

Participants

22 women (mean age 21.7 ± 3.9 years) with a history of trauma, and 20 no-trauma controls (mean age 21.9 ± 4.8 years).

Measures

Trauma exposure and trauma-related symptoms were assessed during structured clinical interview. White matter integrity in the anterior cingulum, parahippocampal cingulum, and uncinate fasciculus was measured using diffusion weighted imaging. Amygdala response to novel and familiar affective scenes was measured with functional magnetic resonance imaging.

Results

Trauma-exposed women showed less discrimination between novel and familiar negative images in the amygdala compared to no-trauma controls. In trauma-exposed women, less amygdala discrimination between novel and familiar affective images was associated with less structural integrity in the anterior cingulum, but was not associated with structural integrity of the parahippocampal cingulum or the uncinate fasciculus.

Conclusions

The anterior cingulum might play an important role in impaired novelty discrimination for affective information in the amygdala. This impairment is potentially driven by inefficient habituation and could contribute to persistent behavioral hypervigilance following trauma exposure.

•

Trauma-exposed women showed impaired amygdala novelty discrimination for negative images.

•

Less novelty discrimination in the amygdala was associated with less anterior cingulum integrity.

•

The anterior cingulum might play a role in trauma-related behavioral hypervigilance.

Facilitating Fear-Based Memory Extinction With Dexamethasone: A Randomized Controlled Trial in Male Veterans With Combat-Related PTSD

OBJECTIVE

Animal and preliminary human studies have demonstrated that glucocorticoids enhance the extinction of fear memories. Impaired extinction of fear memories is a critical component in the development and maintenance of posttraumatic stress disorder (PTSD). The purpose of this translational study was to determine the effectiveness of pairing a glucocorticoid with trauma memory reactivation as a novel intervention to treat PTSD and to measure the duration of the effect.

METHOD

A total of 54 male veterans with combat-related PTSD in this double-blind, randomized, placebo-controlled trial received either four weekly glucocorticoid (dexamethasone [DEX]) or placebo administrations paired with a 45-second trauma memory reactivation task. PTSD and depressive symptom severity were assessed at baseline and at one three, and six months.

RESULTS

Trauma memory activation paired with DEX versus trauma memory activation paired with placebo demonstrated a significantly greater reduction of PTSD symptoms for DEX at the one-month (p = .037) and three-month (p = .036) posttreatment assessments, but the difference was no longer evident at six months. DEX showed a nonsignificantly greater reduction of PTSD symptoms than placebo over the course of the study (p = .067). Significantly more veterans in the DEX group lost their diagnosis of PTSD at one month posttreatment compared to the placebo group, but the difference was not maintained at three or six months. DEX had no effect on depression symptoms.

CONCLUSIONS

Despite insufficient power to test differences in PTSD symptom reduction, findings suggest that this novel intervention may have potential for treatment of combat-related PTSD.

Morphological brain measures of cortico-limbic inhibition related to resilience

Resilience is the ability to adequately adapt and respond to homeostatic perturbations. Although resilience has been associated with positive health outcomes, the neuro-biological basis of resilience is poorly understood. The aim of the study was to identify associations between regional brain morphology and trait resilience with a focus on resilience-related morphological differences in brain regions involved in cortico-limbic inhibition. The relationship between resilience and measures of affect were also investigated. Forty-eight healthy subjects completed structural MRI scans. Self-reported resilience was measured using the Connor and Davidson Resilience Scale. Segmentation and regional parcellation of images was performed to yield a total of 165 regions. Gray matter volume (GMV), cortical thickness, surface area, and mean curvature were calculated for each region. Regression models were used to identify associations between morphology of regions belonging to executive control and emotional arousal brain networks and trait resilience (total and subscales) while controlling for age, sex, and total GMV. Correlations were also conducted between resilience scores and affect scores. Significant associations were found between GM changes in hypothesized brain regions (subparietal sulcus, intraparietal sulcus, amygdala, anterior mid cingulate cortex, and subgenual cingulate cortex) and resilience scores. There were significant positive correlations between resilience and positive affect and negative correlations with negative affect. Resilience was associated with brain morphology of regions involved in cognitive and affective processes related to cortico-limbic inhibition. Brain signatures associated with resilience may be a biomarker of vulnerability to disease. © 2016 Wiley Periodicals, Inc.

Molecular Neuroimaging in Posttraumatic Stress Disorder

Over the past decade, an increasing number of neuroimaging studies have provided insight into the neurobiological mechanisms of posttraumatic stress disorder (PSTD). In particular, molecular neuroimaging techniques have been employed in examining metabolic and neurochemical processes in PTSD. This article reviews molecular neuroimaging studies in PTSD and focuses on findings using three imaging modalities including positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance spectroscopy (MRS). Although there were some inconsistences in the findings, patients with PTSD showed altered cerebral metabolism and perfusion, receptor bindings, and metabolite profiles in the limbic regions, medial prefrontal cortex, and temporal cortex. Studies that have investigated brain correlates of treatment response are also reviewed. Lastly, the limitations of the molecular neuroimaging studies and potential future research directions are discussed.

Memory under stress: from single systems to network changes

Stressful events have profound effects on learning and memory. These effects are mainly mediated by catecholamines and glucocorticoid hormones released from the adrenals during stressful encounters. It has been known for long that both catecholamines and glucocorticoids influence the functioning of the hippocampus, a critical hub for episodic memory. However, areas implicated in other forms of memory, such as the insula or the dorsal striatum, can be affected by stress as well. Beyond changes in single memory systems, acute stress triggers the reconfiguration of large scale neural networks which sets the stage for a shift from thoughtful, 'cognitive' control of learning and memory toward more reflexive, 'habitual' processes. Stress-related alterations in amygdala connectivity with the hippocampus, dorsal striatum, and prefrontal cortex seem to play a key role in this shift. The bias toward systems proficient in threat processing and the implementation of well-established routines may facilitate coping with an acute stressor. Overreliance on these reflexive systems or the inability to shift flexibly between them, however, may represent a risk factor for psychopathology in the long-run.

Affect and neural activity in women with PTSD during a task of emotional interference

BACKGROUND

The current study sought to determine the relationship between self-reported dimensions of affect and activation in brain regions associated with emotion regulation in PTSD during a task of non-conscious emotional processing in interpersonal trauma survivors with PTSD and healthy controls.

METHODS

Participants included 52 women diagnosed with PTSD and 18 female healthy controls. All participants completed a clinical assessment including the SCID, CAPS, and PANAS followed by a functional MRI assessment including a task of implicit emotional conflict.

RESULTS

When PTSD participants were oriented to fearful faces, negative affect (NA) was inversely related to activation in the left amygdala and positive affect (PA) was inversely related to activation in the right amygdala. When ignoring fearful faces, NA was positively associated with activation in the right parahippocampal gyrus and PA was inversely related to activation in the left hippocampus. Similar results were observed in healthy controls regarding PA. However, NA was not significantly related to any region of interest in healthy controls.

LIMITATIONS

Limitations include the homogeneity of the healthy controls with regard to racial diversity, results may only be specific to female interpersonal trauma survivors with PTSD, and neutral faces within the conflict task may be perceived as negative by clinical samples.

CONCLUSIONS

Persistent, increased NA may represent a proxy for disruptions in emotional processing in interpersonal trauma survivors with PTSD. As such, clinicians may prioritize increasing emotional awareness through emotion regulation and/or distress tolerance strategies in this population.